1. Field of the Invention
The present invention relates to a printer and a printer information inquiry communication system thereof for automatically checking functions or the like of a printer connected to a main central processing unit.
2. Description of the Prior Art
Most conventional printers have different switches such as DIP switches (Dual In-line Package switches for printed circuit board mounting) or functions equivalent to these different switches. By operating the DIP switches, printer functions such as the type and size of characters and line spacing can be selected. More specifically, a user switches the DIP switches for each different application. In different types of printer, code systems differ from each other. Each code system controls the characters and operation of the corresponding printer. A central processing unit in a main device must select control codes or the like in accordance with the type of printer or the internal status. For example, when printers which are and are not capable of paper feed by a carriage return code (CR code) are connected to the main central processing unit, the main central processing unit must select whether to produce an LF code after each CR code. That is, when the CR code is supplied to a printer which does not feed paper in response thereto, an LF code must be sent after the CR code. However, when the CR code is supplied to a printer which feeds paper in response thereto, an LF code need not be sent after the CR code. Conventionally, when a main central processing unit and printers are connected through a parallel interface, these pieces of information cannot be checked by the central processing unit in the main device. This is because unidirectional data signal lines are used to transfer data only from the main central processing unit to the printers. For this reason, in the conventional printer, the operator manually enters these pieces of information into the central processing unit in the main device.